ISS023-E-021506 (11 April 2010) --- NASA astronaut Rick Mastracchio, STS-131 mission specialist, participates in the mission's second session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the seven-hour, 26-minute spacewalk, Mastracchio and astronaut Clayton Anderson (out of frame), mission specialist, unhooked and removed the depleted ammonia tank and installed a 1,700-pound ammonia tank on the station’s Starboard 1 truss, completing the second of a three-spacewalk coolant tank replacement process.

ISS023-E-021515 (11 April 2010) --- NASA astronaut Rick Mastracchio, STS-131 mission specialist, participates in the mission's second session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the seven-hour, 26-minute spacewalk, Mastracchio and astronaut Clayton Anderson (out of frame), mission specialist, unhooked and removed the depleted ammonia tank and installed a 1,700-pound ammonia tank on the station’s Starboard 1 truss, completing the second of a three-spacewalk coolant tank replacement process.

ISS023-E-021503 (11 April 2010) --- NASA astronaut Rick Mastracchio, STS-131 mission specialist, participates in the mission's second session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the seven-hour, 26-minute spacewalk, Mastracchio and astronaut Clayton Anderson (out of frame), mission specialist, unhooked and removed the depleted ammonia tank and installed a 1,700-pound ammonia tank on the station’s Starboard 1 truss, completing the second of a three-spacewalk coolant tank replacement process.

ISS023-E-021510 (11 April 2010) --- NASA astronaut Rick Mastracchio, STS-131 mission specialist, participates in the mission's second session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the seven-hour, 26-minute spacewalk, Mastracchio and astronaut Clayton Anderson (out of frame), mission specialist, unhooked and removed the depleted ammonia tank and installed a 1,700-pound ammonia tank on the station’s Starboard 1 truss, completing the second of a three-spacewalk coolant tank replacement process.

ISS023-E-021535 (11 April 2010) --- NASA astronaut Rick Mastracchio, STS-131 mission specialist, participates in the mission's second session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the seven-hour, 26-minute spacewalk, Mastracchio and astronaut Clayton Anderson (out of frame), mission specialist, unhooked and removed the depleted ammonia tank and installed a 1,700-pound ammonia tank on the station’s Starboard 1 truss, completing the second of a three-spacewalk coolant tank replacement process.

ISS023-E-020981 (9 April 2010) --- NASA astronaut Rick Mastracchio, STS-131 mission specialist, participates in the mission's first session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the six-hour, 27-minute spacewalk, Mastracchio and astronaut Clayton Anderson (out of frame), mission specialist, helped move a new 1,700-pound ammonia tank from space shuttle Discovery’s cargo bay to a temporary parking place on the station, retrieved an experiment from the Japanese Kibo Laboratory exposed facility and replaced a Rate Gyro Assembly on one of the truss segments.

ISS023-E-021525 (11 April 2010) --- NASA astronaut Rick Mastracchio, STS-131 mission specialist, participates in the mission's second session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the seven-hour, 26-minute spacewalk, Mastracchio and astronaut Clayton Anderson (out of frame), mission specialist, unhooked and removed the depleted ammonia tank and installed a 1,700-pound ammonia tank on the station’s Starboard 1 truss, completing the second of a three-spacewalk coolant tank replacement process.

ISS023-E-022880 (13 April 2010) --- NASA astronaut Rick Mastracchio, STS-131 mission specialist, participates in the mission's third and final session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the six-hour, 24-minute spacewalk, Mastracchio and astronaut Clayton Anderson (out of frame), mission specialist, hooked up fluid lines of the new 1,700-pound tank, retrieved some micrometeoroid shields from the Quest airlock’s exterior, relocated a portable foot restraint and prepared cables on the Zenith 1 truss for a spare Space to Ground Ku-Band antenna, two chores required before space shuttle Atlantis' STS-132/ULF-4 mission in May.

ISS023-E-021537 (11 April 2010) --- NASA astronaut Rick Mastracchio, STS-131 mission specialist, participates in the mission's second session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the seven-hour, 26-minute spacewalk, Mastracchio and astronaut Clayton Anderson (out of frame), mission specialist, unhooked and removed the depleted ammonia tank and installed a 1,700-pound ammonia tank on the station’s Starboard 1 truss, completing the second of a three-spacewalk coolant tank replacement process.

ISS023-E-022882 (13 April 2010) --- NASA astronaut Rick Mastracchio, STS-131 mission specialist, participates in the mission's third and final session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the six-hour, 24-minute spacewalk, Mastracchio and astronaut Clayton Anderson (out of frame), mission specialist, hooked up fluid lines of the new 1,700-pound tank, retrieved some micrometeoroid shields from the Quest airlock’s exterior, relocated a portable foot restraint and prepared cables on the Zenith 1 truss for a spare Space to Ground Ku-Band antenna, two chores required before space shuttle Atlantis' STS-132/ULF-4 mission in May.

ISS023-E-022870 (13 April 2010) --- NASA astronaut Rick Mastracchio, STS-131 mission specialist, participates in the mission's third and final session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the six-hour, 24-minute spacewalk, Mastracchio and astronaut Clayton Anderson (out of frame), mission specialist, hooked up fluid lines of the new 1,700-pound tank, retrieved some micrometeoroid shields from the Quest airlock’s exterior, relocated a portable foot restraint and prepared cables on the Zenith 1 truss for a spare Space to Ground Ku-Band antenna, two chores required before space shuttle Atlantis' STS-132/ULF-4 mission in May.

ISS023-E-021543 (11 April 2010) --- The nose and forward cabin of the docked space shuttle Discovery is featured in this image photographed by a spacewalker during the STS-131 mission's second session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station.

ISS023-E-021529 (11 April 2010) --- NASA astronaut Rick Mastracchio, STS-131 mission specialist, participates in the mission's second session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the seven-hour, 26-minute spacewalk, Mastracchio and astronaut Clayton Anderson (out of frame), mission specialist, unhooked and removed the depleted ammonia tank and installed a 1,700-pound ammonia tank on the station’s Starboard 1 truss, completing the second of a three-spacewalk coolant tank replacement process.

ISS023-E-020986 (9 April 2010) --- NASA astronaut Rick Mastracchio, STS-131 mission specialist, participates in the mission's first session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the six-hour, 27-minute spacewalk, Mastracchio and astronaut Clayton Anderson (out of frame), mission specialist, helped move a new 1,700-pound ammonia tank from space shuttle Discovery’s cargo bay to a temporary parking place on the station, retrieved an experiment from the Japanese Kibo Laboratory exposed facility and replaced a Rate Gyro Assembly on one of the truss segments.

ISS023-E-020983 (9 April 2010) --- NASA astronaut Rick Mastracchio, STS-131 mission specialist, participates in the mission's first session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the six-hour, 27-minute spacewalk, Mastracchio and astronaut Clayton Anderson (out of frame), mission specialist, helped move a new 1,700-pound ammonia tank from space shuttle Discovery’s cargo bay to a temporary parking place on the station, retrieved an experiment from the Japanese Kibo Laboratory exposed facility and replaced a Rate Gyro Assembly on one of the truss segments.